Structure prediction for nanoscale magic-size CdSe clusters from a new efficient structure-searching strategy.

Area of Science:

• Materials Science
• Computational Chemistry
• Nanotechnology

Background:

• Magic-size clusters (MSCs) are vital in quantum dot (QD) synthesis, exhibiting unique optical properties and stability.
• Understanding MSC structures is crucial, but often limited by the lack of single-crystal data.
• Previous studies have not fully elucidated the structural diversity and stability of CdSe MSCs.

Purpose of the Study:

• To perform structural searching and prediction for specific Cadmium Selenide (CdSe) magic-size clusters (MSCs) with sizes n=13, 19, 33, and 34.
• To develop and validate an efficient computational workflow for identifying stable MSC structures.
• To provide insights into the structural evolution and transformation mechanisms of CdSe MSCs.

Main Methods:

• Integration of Ab Initio Random Structure Searching (AIRSS) for exploring structural possibilities.
• Application of the semi-empirical extended tight binding (xTB) method for initial energy calculations.
• Utilization of density functional theory (DFT) for accurate structural optimization and energy evaluation.

Main Results:

• Identified core@cage as the dominant topology for the lowest energy isomers of the studied CdSe MSCs.
• Discovered a novel, stable adamantane-type Cd4Se6 core structure for the (CdSe)34 cluster, reported for the first time.
• Generated numerous new and more stable structural candidates for larger CdSe MSCs, expanding known structural landscape.

Conclusions:

• The developed computational strategy effectively predicts stable structures for CdSe MSCs.
• The core@cage topology represents a significant finding for CdSe MSCs, challenging previous assumptions.
• This work offers valuable insights into the fundamental structures of CdSe MSCs and their potential formation pathways.